convert C-style (void) parameter lists to C++ style ()

src/key.h

@@ -181,12 +181,12 @@ struct CExtKey {
 };
 
 /** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
-void ECC_Start(void);
+void ECC_Start();
 
 /** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
-void ECC_Stop(void);
+void ECC_Stop();
 
 /** Check that required EC support is available at runtime. */
-bool ECC_InitSanityCheck(void);
+bool ECC_InitSanityCheck();
 
 #endif // BITCOIN_KEY_H